Field of the Invention
The present invention relates to a vehicle body structure with an impact absorbing part, which includes an impact absorbing part extending from an end side of a vehicle body frame member in a longitudinal (front-rear) longitudinal direction of the vehicle body.
Description of the Related Art
There is known a vehicle body structure in which bumper beam extensions (to be referred to as impact absorbing parts hereinafter) project from the front ends of left and right front side frames, and a bumper beam is put between the left and right impact absorbing parts.
According to the vehicle body structure, when the impact absorbing parts are deformed by a collision load (to be referred to as a light collision load) input by a light collision, the light energy of the light collision load can be absorbed by the impact absorbing parts. This can suppress deformation of the front side frames and reduce the repair cost of the vehicle.
In a frontal collision or offset collision of a high collision speed more than a light collision, passengers are considered to be more suitably protected using the impact absorbing parts. To do this, it is necessary to raise the rigidity of the impact absorbing parts to some extent and absorb initial energy at an early stage of a frontal collision or offset collision.
This makes it possible to reduce the deceleration (acceleration) applied to the passengers upon a frontal collision or offset collision.
Recently, vehicles are growing in which a platform (body frame) is diverted to a plurality of automobile models. Hence, to cope with each automobile model, the arrangement locations of the front side frames are determined. In addition, to prevent damage to a radiator and the like upon a light collision, the shape and arrangement location of the bumper beam are determined in accordance with the design of each automobile model.
Hence, the longitudinal direction length of each impact absorbing part that intervenes between the bumper beam and the front side frame is automatically determined.
For this reason, when a platform is employed, for example, the length of each impact absorbing part may increase in the longitudinal direction of the vehicle body. If, in this state, the rigidity of the impact absorbing parts is ensured to absorb a light collision load upon a light collision and absorb initial energy of a frontal collision or offset collision, the rigidity of the impact absorbing parts is thought to exceed the load bearing ability of the platform (body frame).
It is therefore difficult to ensure the rigidity of the impact absorbing parts to absorb the initial energy of a frontal collision or offset collision.
There is also proposed a vehicle body structure in which an impact absorbing part is formed from an upper member having an inverted U-shaped section, a lower member having a U-shaped section, and a reinforcing member (for example, Japanese Patent No. 5168477).
That is, the inner wall of the upper member formed into an inverted U-shaped sectional shape, the inner wall of the lower member formed into a U-shaped sectional shape, and the inner flange of the reinforcing member are joined in a state in which the three members are overlaid. Similarly, the outer wall of the upper member, the outer wall of the lower member, and the outer flange of the reinforcing member are joined in a state in which the three members are overlaid.
An almost rectangular tubular body is thus formed by the upper member and the lower member, and the reinforcing member is provided in the tubular body.
Additionally, at the front portion of the tubular body, a plurality of beads are formed to extend in the vehicle width direction on the upper portion, the lower portion, the inner wall, and the outer wall. It is therefore possible to crush, in the longitudinal direction of the vehicle body, the front portion of the tubular body by a light collision load input by a light collision and absorb the light collision load.
Furthermore, at the rear portion of the tubular body, a plurality of beads are formed to extend in the longitudinal direction of the vehicle body on the inner wall and the outer wall. In addition, the reinforcing member is provided in the tubular body. Hence, the rigidity of the rear portion of the tubular body is ensured to absorb the initial energy of a frontal collision or offset collision.
According to the impact absorbing part of Japanese Patent No. 5168477, it is possible to absorb light energy upon a light collision and also absorb the initial energy of a frontal collision or offset collision.
In the impact absorbing part of Japanese Patent No. 5168477, however, the reinforcing member needs to be provided in the tubular body to enable absorption of light energy upon a light collision or the initial energy of a frontal collision or offset collision. This leads to an increase in the number of parts, which impedes suppression of an increase in cost and weight.